Piano hammer felt



Dec. 30, 1969 L. JOHNSON IZ IANO HAMMER FELT Filed May 2'7, 1968 FIG. I.

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INVENTOR [RNEST L. Jam/$0M ATTORNEYS 3,487,429 PIANO HAMMER FELT Ernest L. Johnson, Rye, N.Y., assignor to GAF Corporation, a corporation of Delaware Filed May 27, 1968, Ser. No. 732,193 Int. Cl. G10c 3/18 US. Cl. 84-254 14 Claims ABSTRACT OF THE DISCLOSURE Felt for a piano hammer comprising a blend of wool and thermoplastic fibers.

The present invention relates to a piano hammer, more particularly, to the felt covering or striking surface of the hammer composed of a blend of wool and thermoplastic fibers and a felt having such a composition.

One of the major operating components of a piano is the hammer, which is usually provided with a felt-covered head so that actuation of the hammer by depression of one of the piano keys will cause the felt head to strike a corresponding piano wire. Since the tone of a piano and the tonal quality of each note may be affected by the construction and density of the hammer, many attempts have been made to improve the hammer construction and especially the felt contact surface. The felt striking member of the hammer generally becomes worn or damaged and flattened under continuous use to such an extent as to impair the tone. In addition, the striking members have been formed of .many different materials in an attempt to provide a gradation of elasticity as well as longlasting hammers which are highly resistant to wear or other damage.

One of the objects of the present invention is to provide a piano hammer of improved striking characteristics.

Another object of the present invention is to provide a simple yet long-lasting felt striking surface of controlled density for a piano hammer.

In one aspect of the present invention, there is provided a piano hammer having a hammer head mounted on the end of a shank and a striking member fastened to the hammer head. The striking member is formed from a felt material comprising a blend of high-grade wool and thermoplastic fibers. The thermoplastic fibers may either be uniformly distributed throughout the felt or they may be concentrated along the exterior annulus or the interior annulus or both annuli of the felt pad. Optimum results have been obtained when the thermoplastic fibers comprise 5 to 30 percent of the composition of the felt or any portion of the felt containing thermoplastic fiber.

In a further aspect, the density and hardness of the hammer felt can be varied from the base to the treble end of the scale. That is, the hammer felt can be made softer or of lower density at the base end and harder or denser at the treble end.

Other objects, advantages and features of the present invention will become apparent upon reference to the accompanying description when taken in conjunction with the following drawing which are merely exemplary.

In the drawing:

FIG. 1 is a fragmentary elevational view of a piano hammer and showing the striking portion of the hammer head in section; and

FIG. 2 shows a sheet of felt to be cut into strips.

There is shown in the drawing a conventional piano hammer assembly indicated generally at and comprising a conventional hammer head 12 mounted on the upper end of a shank 13.

The forward or striking end of hammer head 12 is United States Patent 0 "ice tapered as indicated at 14 and a striking member generally indicated at 15 is adhered to the hammer head 12 by a suitable adhesive at 16. In this particular embodiment of the invention, the striking member 15 is composed of an inner layer 17 and an outer layer 18, but it is to be understood that the member may comprise only a single layer of felt material.

The inner layer 17, or underfelt, can be composed of a softer material, having a lower density than the material comprising outer layer 18.

In accordance with the present invention, outer layer 18 is a felt composed of a blend of high-grade virgin sheeps wool and a binder of thermoplastic fibers. The thermoplastic fibers preferably comprise 5 to 30 percent of the composition of the felt.

The binders or thermoplastic fibers may comprise cellulose acetate fibers or other thermoplastic fibers such as polyethylene, polypropylene, and polyvinyl chloride. The fibers may be uniformly distributed throughout the felt composition or their distribution may be limited to one or both of the exterior annulus 15' and the interior annulus 15" of the outer layer 18. The presence of the fibers in the felt enhance considerably the strength and durability of the felt but in no way hinder attaching the felt to the piano hammer head.

In fastening the striking member to the hammer head, the member is adhered to the hammer head by a suitable glue under conditions of tension, pressure and temperature as is well known in the art. The hammer head assembly with the glue applied between the hammer head and the felt is held at a temperature of between about 200 to 300 degrees F. depending on the type of thermoplastic binder fiber used. The time of holding the felt at said temperature will depend upon the weight and thickness of the felt. Also, for any given weight or thickness, the time and temperature involved can be varied to change the degree of fusing and final hardness of the finished piano hammer. The fusing temperature is selected according to the softening temperature of the thermoplastic fiber so that during the setting of the glue and molding of the hammer, the thermoplastic fibers will fuse with the wool fibers of the felt composition. As a result, there will be obtained a strong felt structure of controlled density and hardness which will have a long operating life of durable tonal quality throughout the operation of the piano.

If desired, the density of the striking face or part of the hammer can be varied according to the portion of the scale of the strings to be struck. As an example, the striking member felt can have 5 percent thermoplastic fiber for the base portion, 7 percent thermoplastic fiber for the tenor portion and 10 percent for the treble portion. FIG. 2 illustrates a wedge of fiber that can be cut to provide the striking member.

The heating of the felt composition to the proper tem perature for molding the felt or setting of the glue will result in activation of the thermoplastic binder fibers to provide an improved striking member felt member composition.

What is claimed is:

1. A piano hammer comprising a hammer head and a striking member fastened to said hammer head, said striking member comprising a blend of fibers and thermoplastic fibers bonded therewith.

2. A piano hammer as claimed in claim 1 wherein said striking member comprises a blend of wool fibers and 5 to 30% thermoplastic fibers.

3. A piano hammer as claimed in claim 1 wherein said thermoplastic fibers are uniformly distributed throughout said striking member.

4. A piano hammer as claimed in claim 1 wherein said thermoplastic fibers are concentrated in one annulus of said striking member.

5. A piano hammer as claimed in claim 4 wherein the thermoplastic fibers are concentrated adjacent both annuli of the striking member.

6. A piano hammer as claimed in claim 1 wherein said thermoplastic fibers are selected from the group consisting of polyethylene, polypropylene, and polyvinyl chloride.

7. A piano hammer as claimed in claim 1 wherein said member comprises a blend of 90 percent virgin wool and 10 percent of thermoplastic fibers.

8. A piano hammer as claimed in claim 1 wherein the blend of fibers includes about 5 percent of thermoplastic fibers adjacent the base portion of the scale, about 7 percent adjacent the tenor portion of the scale and about 10 percent adjacent the treble portion of the scale.

9. A piano hammer felt composition consisting essentially of a blend of wool and 5 to 30 percent of thermoplastic fibers.

10. A piano hammer felt as claimed in claim 9 wherein said felt comprises a blend of 90 percent of wool and 10 percent thermoplastic fibers.

11. A piano hammer felt as claimed in claim 9 wherein said thermoplastic fibers are uniformly distributed throughout said wool.

12. A piano hammer felt as claimed in claim 9 wherein said thermoplastic fibers are adjacent one annulus of the striking member.

13. A piano hammer felt as claimed in claim 9 wherein the thermoplastic fibers are adjacent both annuli of the striking member.

14. A piano hammer felt as claimed in claim 9 wherein there is about 5 percent thermoplastic fibers adjacent the base portion of the scale, about 7 percent adjacent the tenor portion of the scale and 10 percent adjacent the treble portion of the scale.

References Cited UNITED STATES PATENTS 1,374,974 4/1921 Wrozina 84-254 2,357,392 9/1944 Francis 156371 2,483,406 10/ 1949 Francis 156371 RICHARDSON B. WILKINSON, Primary Examiner LAWRENCE R. FRANKLIN, Assistant Examiner 

